// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// File provides direct encoding of bits with arithmetic encoder interface.
#ifndef DRACO_CORE_BIT_CODERS_FOLDED_INTEGER_BIT_DECODER_H_
#define DRACO_CORE_BIT_CODERS_FOLDED_INTEGER_BIT_DECODER_H_

#include <vector>

#include "draco/core/decoder_buffer.h"

namespace draco {

// See FoldedBit32Encoder for more details.
template <class BitDecoderT>
class FoldedBit32Decoder {
  public:
    FoldedBit32Decoder() {}
    ~FoldedBit32Decoder() {}

    // Sets |source_buffer| as the buffer to decode bits from.
    bool StartDecoding(DecoderBuffer *source_buffer) {
        for (int i = 0; i < 32; i++) {
            if (!folded_number_decoders_[i].StartDecoding(source_buffer))
                return false;
        }
        return bit_decoder_.StartDecoding(source_buffer);
    }

    // Decode one bit. Returns true if the bit is a 1, otherwise false.
    bool DecodeNextBit() {
        return bit_decoder_.DecodeNextBit();
    }

    // Decode the next |nbits| and return the sequence in |value|. |nbits| must be
    // > 0 and <= 32.
    void DecodeLeastSignificantBits32(int nbits, uint32_t *value) {
        uint32_t result = 0;
        for (int i = 0; i < nbits; ++i) {
            const bool bit = folded_number_decoders_[i].DecodeNextBit();
            result = (result << 1) + bit;
        }
        *value = result;
    }

    void EndDecoding() {
        for (int i = 0; i < 32; i++) {
            folded_number_decoders_[i].EndDecoding();
        }
        bit_decoder_.EndDecoding();
    }

  private:
    void Clear() {
        for (int i = 0; i < 32; i++) {
            folded_number_decoders_[i].Clear();
        }
        bit_decoder_.Clear();
    }

    std::array<BitDecoderT, 32> folded_number_decoders_;
    BitDecoderT bit_decoder_;
};

}  // namespace draco

#endif  // DRACO_CORE_BIT_CODERS_FOLDED_INTEGER_BIT_DECODER_H_
